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Commit0e5e167

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Collect and use element-frequency statistics for arrays.
This patch improves selectivity estimation for the array <@, &&, and @>(containment and overlaps) operators. It enables collection of statisticsabout individual array element values by ANALYZE, and introducesoperator-specific estimators that use these stats. In addition,ScalarArrayOpExpr constructs of the forms "const = ANY/ALL (array_column)"and "const <> ANY/ALL (array_column)" are estimated by treating them asvariants of the containment operators.Since we still collect scalar-style stats about the array values as awhole, the pg_stats view is expanded to show both these stats and thearray-style stats in separate columns. This creates an incompatible changein how stats for tsvector columns are displayed in pg_stats: the statsabout lexemes are now displayed in the array-related columns instead of theoriginal scalar-related columns.There are a few loose ends here, notably that it'd be nice to be able tosuppress either the scalar-style stats or the array-element stats forcolumns for which they're not useful. But the patch is in good enoughshape to commit for wider testing.Alexander Korotkov, reviewed by Noah Misch and Nathan Boley
1 parent34c9784 commit0e5e167

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24 files changed

+2341
-168
lines changed

24 files changed

+2341
-168
lines changed

‎doc/src/sgml/catalogs.sgml‎

Lines changed: 40 additions & 11 deletions
Original file line numberDiff line numberDiff line change
@@ -5354,9 +5354,9 @@
53545354
Column data values of the appropriate kind for the
53555355
<replaceable>N</>th <quote>slot</quote>, or null if the slot
53565356
kind does not store any data values. Each array's element
5357-
values are actually of the specific column's data type,so there
5358-
is no way to define these columns'type more specifically than
5359-
<type>anyarray</>.
5357+
values are actually of the specific column's data type,or a related
5358+
type such as an array's elementtype, so there is no way to define
5359+
these columns' type more specifically than<type>anyarray</>.
53605360
</entry>
53615361
</row>
53625362
</tbody>
@@ -8291,8 +8291,6 @@
82918291
<entry>
82928292
A list of the most common values in the column. (Null if
82938293
no values seem to be more common than any others.)
8294-
For some data types such as <type>tsvector</>, this is a list of
8295-
the most common element values rather than values of the type itself.
82968294
</entry>
82978295
</row>
82988296

@@ -8301,12 +8299,9 @@
83018299
<entry><type>real[]</type></entry>
83028300
<entry></entry>
83038301
<entry>
8304-
A list of the frequencies of the most common values or elements,
8302+
A list of the frequencies of the most common values,
83058303
i.e., number of occurrences of each divided by total number of rows.
83068304
(Null when <structfield>most_common_vals</structfield> is.)
8307-
For some data types such as <type>tsvector</>, it can also store some
8308-
additional information, making it longer than the
8309-
<structfield>most_common_vals</> array.
83108305
</entry>
83118306
</row>
83128307

@@ -8338,13 +8333,47 @@
83388333
type does not have a <literal>&lt;</> operator.)
83398334
</entry>
83408335
</row>
8336+
8337+
<row>
8338+
<entry><structfield>most_common_elems</structfield></entry>
8339+
<entry><type>anyarray</type></entry>
8340+
<entry></entry>
8341+
<entry>
8342+
A list of non-null element values most often appearing within values of
8343+
the column. (Null for scalar types.)
8344+
</entry>
8345+
</row>
8346+
8347+
<row>
8348+
<entry><structfield>most_common_elem_freqs</structfield></entry>
8349+
<entry><type>real[]</type></entry>
8350+
<entry></entry>
8351+
<entry>
8352+
A list of the frequencies of the most common element values, i.e., the
8353+
fraction of rows containing at least one instance of the given value.
8354+
Two or three additional values follow the per-element frequencies;
8355+
these are the minimum and maximum of the preceding per-element
8356+
frequencies, and optionally the frequency of null elements.
8357+
(Null when <structfield>most_common_elems</structfield> is.)
8358+
</entry>
8359+
</row>
8360+
8361+
<row>
8362+
<entry><structfield>elem_count_histogram</structfield></entry>
8363+
<entry><type>real[]</type></entry>
8364+
<entry></entry>
8365+
<entry>
8366+
A histogram of the counts of distinct non-null element values within the
8367+
values of the column, followed by the average number of distinct
8368+
non-null elements. (Null for scalar types.)
8369+
</entry>
8370+
</row>
83418371
</tbody>
83428372
</tgroup>
83438373
</table>
83448374

83458375
<para>
8346-
The maximum number of entries in the <structfield>most_common_vals</>
8347-
and <structfield>histogram_bounds</> arrays can be set on a
8376+
The maximum number of entries in the array fields can be controlled on a
83488377
column-by-column basis using the <command>ALTER TABLE SET STATISTICS</>
83498378
command, or globally by setting the
83508379
<xref linkend="guc-default-statistics-target"> run-time parameter.

‎src/backend/catalog/heap.c‎

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -1182,7 +1182,7 @@ heap_create_with_catalog(const char *relname,
11821182
F_ARRAY_SEND,/* array send (bin) proc */
11831183
InvalidOid,/* typmodin procedure - none */
11841184
InvalidOid,/* typmodout procedure - none */
1185-
InvalidOid,/* analyze procedure - default */
1185+
F_ARRAY_TYPANALYZE,/*arrayanalyze procedure */
11861186
new_type_oid,/* array element type - the rowtype */
11871187
true,/* yes, this is an array type */
11881188
InvalidOid,/* this has no array type */

‎src/backend/catalog/system_views.sql‎

Lines changed: 34 additions & 9 deletions
Original file line numberDiff line numberDiff line change
@@ -117,29 +117,54 @@ CREATE VIEW pg_stats AS
117117
stawidthAS avg_width,
118118
stadistinctAS n_distinct,
119119
CASE
120-
WHEN stakind1IN (1,4) THEN stavalues1
121-
WHEN stakind2IN (1,4) THEN stavalues2
122-
WHEN stakind3IN (1,4) THEN stavalues3
123-
WHEN stakind4IN (1,4) THEN stavalues4
120+
WHEN stakind1=1 THEN stavalues1
121+
WHEN stakind2=1 THEN stavalues2
122+
WHEN stakind3=1 THEN stavalues3
123+
WHEN stakind4=1 THEN stavalues4
124+
WHEN stakind5=1 THEN stavalues5
124125
ENDAS most_common_vals,
125126
CASE
126-
WHEN stakind1IN (1,4) THEN stanumbers1
127-
WHEN stakind2IN (1,4) THEN stanumbers2
128-
WHEN stakind3IN (1,4) THEN stanumbers3
129-
WHEN stakind4IN (1,4) THEN stanumbers4
127+
WHEN stakind1=1 THEN stanumbers1
128+
WHEN stakind2=1 THEN stanumbers2
129+
WHEN stakind3=1 THEN stanumbers3
130+
WHEN stakind4=1 THEN stanumbers4
131+
WHEN stakind5=1 THEN stanumbers5
130132
ENDAS most_common_freqs,
131133
CASE
132134
WHEN stakind1=2 THEN stavalues1
133135
WHEN stakind2=2 THEN stavalues2
134136
WHEN stakind3=2 THEN stavalues3
135137
WHEN stakind4=2 THEN stavalues4
138+
WHEN stakind5=2 THEN stavalues5
136139
ENDAS histogram_bounds,
137140
CASE
138141
WHEN stakind1=3 THEN stanumbers1[1]
139142
WHEN stakind2=3 THEN stanumbers2[1]
140143
WHEN stakind3=3 THEN stanumbers3[1]
141144
WHEN stakind4=3 THEN stanumbers4[1]
142-
ENDAS correlation
145+
WHEN stakind5=3 THEN stanumbers5[1]
146+
ENDAS correlation,
147+
CASE
148+
WHEN stakind1=4 THEN stavalues1
149+
WHEN stakind2=4 THEN stavalues2
150+
WHEN stakind3=4 THEN stavalues3
151+
WHEN stakind4=4 THEN stavalues4
152+
WHEN stakind5=4 THEN stavalues5
153+
ENDAS most_common_elems,
154+
CASE
155+
WHEN stakind1=4 THEN stanumbers1
156+
WHEN stakind2=4 THEN stanumbers2
157+
WHEN stakind3=4 THEN stanumbers3
158+
WHEN stakind4=4 THEN stanumbers4
159+
WHEN stakind5=4 THEN stanumbers5
160+
ENDAS most_common_elem_freqs,
161+
CASE
162+
WHEN stakind1=5 THEN stanumbers1
163+
WHEN stakind2=5 THEN stanumbers2
164+
WHEN stakind3=5 THEN stanumbers3
165+
WHEN stakind4=5 THEN stanumbers4
166+
WHEN stakind5=5 THEN stanumbers5
167+
ENDAS elem_count_histogram
143168
FROM pg_statistic sJOIN pg_class cON (c.oid=s.starelid)
144169
JOIN pg_attribute aON (c.oid= attrelidAND attnum=s.staattnum)
145170
LEFT JOIN pg_namespace nON (n.oid=c.relnamespace)

‎src/backend/commands/analyze.c‎

Lines changed: 5 additions & 7 deletions
Original file line numberDiff line numberDiff line change
@@ -110,8 +110,6 @@ static void update_attstats(Oid relid, bool inh,
110110
staticDatumstd_fetch_func(VacAttrStatsPstats,intrownum,bool*isNull);
111111
staticDatumind_fetch_func(VacAttrStatsPstats,intrownum,bool*isNull);
112112

113-
staticboolstd_typanalyze(VacAttrStats*stats);
114-
115113

116114
/*
117115
*analyze_rel() -- analyze one relation
@@ -476,8 +474,7 @@ do_analyze_rel(Relation onerel, VacuumStmt *vacstmt, bool inh)
476474
for (i=0;i<attr_cnt;i++)
477475
{
478476
VacAttrStats*stats=vacattrstats[i];
479-
AttributeOpts*aopt=
480-
get_attribute_options(onerel->rd_id,stats->attr->attnum);
477+
AttributeOpts*aopt;
481478

482479
stats->rows=rows;
483480
stats->tupDesc=onerel->rd_att;
@@ -490,11 +487,12 @@ do_analyze_rel(Relation onerel, VacuumStmt *vacstmt, bool inh)
490487
* If the appropriate flavor of the n_distinct option is
491488
* specified, override with the corresponding value.
492489
*/
490+
aopt=get_attribute_options(onerel->rd_id,stats->attr->attnum);
493491
if (aopt!=NULL)
494492
{
495-
float8n_distinct=
496-
inh ?aopt->n_distinct_inherited :aopt->n_distinct;
493+
float8n_distinct;
497494

495+
n_distinct=inh ?aopt->n_distinct_inherited :aopt->n_distinct;
498496
if (n_distinct!=0.0)
499497
stats->stadistinct=n_distinct;
500498
}
@@ -1794,7 +1792,7 @@ static intcompare_mcvs(const void *a, const void *b);
17941792
/*
17951793
* std_typanalyze -- the default type-specific typanalyze function
17961794
*/
1797-
staticbool
1795+
bool
17981796
std_typanalyze(VacAttrStats*stats)
17991797
{
18001798
Form_pg_attributeattr=stats->attr;

‎src/backend/commands/typecmds.c‎

Lines changed: 3 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -609,7 +609,7 @@ DefineType(List *names, List *parameters)
609609
F_ARRAY_SEND,/* send procedure */
610610
typmodinOid,/* typmodin procedure */
611611
typmodoutOid,/* typmodout procedure */
612-
InvalidOid,/* analyze procedure - default */
612+
F_ARRAY_TYPANALYZE,/* analyze procedure */
613613
typoid,/* element type ID */
614614
true,/* yes this is an array type */
615615
InvalidOid,/* no further array type */
@@ -1140,7 +1140,7 @@ DefineEnum(CreateEnumStmt *stmt)
11401140
F_ARRAY_SEND,/* send procedure */
11411141
InvalidOid,/* typmodin procedure - none */
11421142
InvalidOid,/* typmodout procedure - none */
1143-
InvalidOid,/* analyze procedure - default */
1143+
F_ARRAY_TYPANALYZE,/* analyze procedure */
11441144
enumTypeOid,/* element type ID */
11451145
true,/* yes this is an array type */
11461146
InvalidOid,/* no further array type */
@@ -1450,7 +1450,7 @@ DefineRange(CreateRangeStmt *stmt)
14501450
F_ARRAY_SEND,/* send procedure */
14511451
InvalidOid,/* typmodin procedure - none */
14521452
InvalidOid,/* typmodout procedure - none */
1453-
InvalidOid,/* analyze procedure - default */
1453+
F_ARRAY_TYPANALYZE,/* analyze procedure */
14541454
typoid,/* element type ID */
14551455
true,/* yes this is an array type */
14561456
InvalidOid,/* no further array type */

‎src/backend/tsearch/ts_selfuncs.c‎

Lines changed: 4 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -220,6 +220,10 @@ mcelem_tsquery_selec(TSQuery query, Datum *mcelem, int nmcelem,
220220
/*
221221
* There should be two more Numbers than Values, because the last two
222222
* cells are taken for minimal and maximal frequency. Punt if not.
223+
*
224+
* (Note: the MCELEM statistics slot definition allows for a third extra
225+
* number containing the frequency of nulls, but we're not expecting that
226+
* to appear for a tsvector column.)
223227
*/
224228
if (nnumbers!=nmcelem+2)
225229
returntsquery_opr_selec_no_stats(query);

‎src/backend/tsearch/ts_typanalyze.c‎

Lines changed: 5 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -377,6 +377,11 @@ compute_tsvector_stats(VacAttrStats *stats,
377377
* able to find out the minimal and maximal frequency without
378378
* going through all the values. We keep those two extra
379379
* frequencies in two extra cells in mcelem_freqs.
380+
*
381+
* (Note: the MCELEM statistics slot definition allows for a third
382+
* extra number containing the frequency of nulls, but we don't
383+
* create that for a tsvector column, since null elements aren't
384+
* possible.)
380385
*/
381386
mcelem_values= (Datum*)palloc(num_mcelem*sizeof(Datum));
382387
mcelem_freqs= (float4*)palloc((num_mcelem+2)*sizeof(float4));

‎src/backend/utils/adt/Makefile‎

Lines changed: 2 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -15,7 +15,8 @@ override CFLAGS+= -mieee
1515
endif
1616
endif
1717

18-
OBJS = acl.o arrayfuncs.o array_userfuncs.o arrayutils.o bool.o\
18+
OBJS = acl.o arrayfuncs.o array_selfuncs.o array_typanalyze.o\
19+
array_userfuncs.o arrayutils.o bool.o\
1920
cash.o char.o date.o datetime.o datum.o domains.o\
2021
enum.o float.o format_type.o\
2122
geo_ops.o geo_selfuncs.o int.o int8.o json.o like.o lockfuncs.o\

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